JPS6073158A - Gear transmission mechanism - Google Patents

Abstract

PURPOSE:To make a transmission mechanism compact, by bending back the tip of a pawl as U, engaging the bent-back portions with pins distant from a shifting shaft, and forming cams on the bent-back portions. CONSTITUTION:The tip of a pawl 20 is bent back as U toward a drum so that the bent-back portions 21, 22 are engaged with pins 14 (14-A-14-F) distant from a shifting shaft 15. The pawl 20 can be optionally moved perpendicularly to the shifting shaft 15. Cams 33, 34, which go over the drum pins 14 perpendicularly to the shifting shaft 15 when the pawl 20 is moved back to the neutral position, are formed on the bent-back portions 21, 22 of the pawl. As a result, the distance between the shifting shaft 15 and the drum, the space of disposition perpendicular to the shifting shaft and that of disposition in the direction of the length of the shifting shaft are reduced so that a transmission mechanism is made compact as a whole.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to an entire external gear transmission mechanism mainly used in two-wheeled motorized vehicles. Generally, this type of transmission mechanism has a change drum and a shift shaft in parallel, a plurality of drum bins are provided at the end of the change drum in parallel to each other at intervals in the circumferential direction, and a ball that is oscillated by the shift shaft is provided at the end of the change drum. The above-mentioned bottle pressure is engaged, and the drum is rotated via the shear bin by the rocking of the ball.

(Prior art and problems) Since the ball is engaged with the drum bin on the side closer to the shift shaft, the distance between the center line of the change drum and the shift shaft must be long, which increases the size of the transmission mechanism. .

Since the ball is provided on the shift shaft so as to be movable in the axial direction, and the ball escapes from the bottle in the axial direction when the ball returns to the neutral position, the axial width of the transmission mechanism becomes long.

(Objective of the Invention) It is an object of the present invention to make the entire transmission mechanism compact by reducing the axial width of the transmission mechanism and the length in the direction perpendicular to the axis.

(Structure of the Invention) (a) A ball is provided on the shift shaft so as to be movable in a direction perpendicular to the shaft, and is urged toward the shift shaft 15 by a spring, and the tip of the ball is folded into a substantially U-shape toward the drum. The folded part engages the bin on the side farther from the shift shaft, and the folded part is formed with a cam that rides over the bin in a direction perpendicular to the shift shaft when the ball returns to the neutral position.

(Example) As shown in FIG. 1, a change drum 1 is rotatably supported by a crankcase 2 via a bearing 3, and a plurality of cam grooves 5 are formed on the outer peripheral surface of the P1 change drum 1. , the bin portion 6a of the shift fork 6 is engaged with each cam 11η5. The shift forks 6tJ and 771 are axially movably supported by the support shaft 8 and engaged with annular grooves of each transmission gear (not shown). That is, change drum 1
By rotating the shift fork 6, the shift fork 6 is moved in the axial direction via the cam groove 5, thereby moving the ffi speed gear in the axial direction and changing speed.

A cam (change) 12 extending outside the crankcase 2 is fixed to the end of the change drum 1 by bolts 13, and the cam 12 has six drum bins l4 (14
-A, l4-B,...) are formed at equal intervals in the circumferential direction. Each bin 14 is parallel to the centerline of the drum 1.

The shift shaft 15 is disposed near the tram 1 in parallel with the shaft 9Al, and is supported by the crankcase 2 and the speed mechanism cover 17 so as to be rotatable nine times. A change pedal 18 is fixed to the end Vc of the shift shaft 15 outside the cover 17, and a pole support plate 19 is integrally fixed to the shift shaft 15 portion inside the cover 17.
The ball 20 for driving the drum is attached to the guide bin 30.3.
1 so as to be movable in a direction perpendicular to the shift shaft 15. The tip end of the ball 20 is bent back toward the drum 1 side with a U-shaped cross section, forming a pair of folded portions 21 and 22 (FIG. 2). The ball 20 is connected to the shift shaft 15
and a spring 23 stretched between the protrusion 20a of the ball 20 and biased toward the shift shaft 15 side.

To explain in detail the structure of the ball 20, the grate 19, etc., in FIG. 2, the grate 19 has two holes 24 and 25 for fixing the kite bin, and
There are two long guide grooves 26 perpendicular to the shift shaft 15.
．． 27 is formed and the guide bin 30.3 is 9.21 hard.
1 pass through guide grooves 26 and 27 and are fixed to holes 24 and 25 of grate 19, respectively. Folded part 2
1° 22 are formed at intervals from each other, and the shift shaft 15 is located between the opposing edges of the double folding portions 21 and 22.
The two drum bins 14-A on the far side.

14-B is sandwiched between them. The folded part 22 on the arrow P direction side is a folded part for downshifting, and the shift shaft 1 is attached to the end face on the shift shaft 15 side as it goes in the arrow P direction.
A cam 34 is formed that moves away from 5. The folded portion 21 on the side in the arrow Q direction is a folded portion for upshifting, and a cam 33 that moves away from the shift shaft 15 in the direction of the arrow Q is formed on its end face on the shift shaft 15 side. A stopper 35 for regulating over-rotation of the tram 1 (bin holder 12) is formed in the play 19, and a regulating window hole 36 is formed for regulating the amount of rotation of the play 19 itself. Furthermore, the return spring locking part 3
7 is formed. Stopper 35 and locking part 37Fi
, protrudes toward the drum l side (holder 12 side).

In FIG. 3, which is a sectional view taken along the line ■-■ in FIG. 37 is sandwiched between both end extensions of the return spring 4o that fits into the shift shaft 15. That is, play) 19 is the circumferential edge of the shift shaft 15 times of the regulating window hole 36 and the bottle 3.
The amount of rotation in the directions of υ, arrows P, and arrows Q is regulated by the contact of 9, and the neutral position (non-operating position) of 9 in FIG. 3 is maintained by the action of return spring 4o.

A recess 43 for drum locking is formed on the outer peripheral surface of the cam (tram) 12 at a portion between each drum bin 14 (14-A, etc.), and a locking roller 45 is engaged with the recess 43. are doing. The row 245 is rotatably supported by a pivot shaft 47 via an arm 46, and is urged toward the center of the p-holter 12 by a tension spring 48. The support shaft 47 is fixed to the crankcase 2.
Further, the spring 48 is stretched between the arm 46 and a protrusion 50 formed on the link case 2.

(Function) When shifting up: (a) By depressing the pedal 18 in FIG. 1, the plate 19 together with the p1 shift shaft 15 is rotated in the direction of arrow P in FIG. 3 against the spring 40. The grate 19 rotates until the circumferential edge of the regulation preparation hole 36 comes into contact with the regulation bin 39 (to the state shown in FIG. 4).

As the ball 20 rotates together with the center (gray) 19, the shift-up folding portion 21 of the ball 20 hooks the drum bin 14-A, causing the drum 1 to rotate in the direction of arrow P'. At this time, the cam (drum) 12 rotates while pushing up the locking roller 45 against the spring 48.
As shown in the figure, the next recess 43 on the arrow q side engages with the roller 45 and locks the cam (drum) 12.

(c) When the ball 20 rotates to the state shown in FIG. 4, the stopper 35 for preventing over-rotation comes into contact with the drum bin 14-B located at the left end in FIG. 4, and prevents the drum l from over-rotating. To prevent.

b) By rotating the drum 1 by 60 degrees in the direction of arrow P' as described above, the shift fork 6 shown in FIG. 1 is moved in the axial direction to shift up.

After the shift up is completed, the grate 19 returns from the position shown in FIG. 4 in the direction of arrow Q due to the restoring force of the return spring 40. Along with play) 19, the ball 20 also rotates from the position shown in Figure 4 in the direction of arrow Q, but in the middle of this, the cam 33 of the shift-up folding part 21 climbs over the drum bin 14-F as shown in Figure '5. At times, the ball 20 moves in a direction away from the shift shaft 15 against the spring 23, and when the folded portion 21 crosses the bin 14-F, the spring 23
The restoring force causes the ball 20 to return to the position on the shift shaft 15 side.

When shifting down: (a) By rotating the shift shaft 15 from the neutral position in FIG. 60°
Move it in the direction of arrow Q'.

(b) The functions of the locking row 245, the regulation preparation hole 36, etc. are the same as in the case of upshifting.

The action of the over-rotation prevention stopper 35 is also the same as in the case of upshifting. However, as shown in FIG. 6, the stopper 35 is located at the right end of the drum bin 1 in FIG.
4-Lock A.

→ When the ball 20 returns from the position shown in FIG. 6 in the direction of arrow P, the cam 34 of the folded portion 22 rides over the drum bin 14-C against the spring 23.

(Effects of the Invention) (1) Since the ball is folded back into a substantially U-shape and the folded part is engaged with the drum bin on the side farther from the shift shaft,
The distance σ between the shift shaft and the center line of the drum can be reduced, and the arrangement space in the direction perpendicular to the shift shaft can be small.

(2) The ball is movable in the direction perpendicular to the shift axis,
A cam is formed on the folded part of the ball so that when the ball returns to the neutral position, it passes over the do and 7 bins in a direction perpendicular to the shift shaft, so the installation space in the length direction of the shift shaft is small. .

(3) As a result of the above items (11 and (2)), the entire transmission becomes significantly more compact.

(4) Since the structure is such that the ball engages with the drum bin on the side farther from the shift shaft, the ball engages with the drum bin on the side closer to the shift shaft, compared to a structure where the ball engages with the drum bin on the side closer to the shift shaft. The mutual deviation between the ball and the ball is small, which makes shifting operations easier. The reason why the above deviation (slip amount) becomes smaller is as follows.
This is because the circumference formed by connecting the drum bins is inscribed in the arcuate locus of movement of the ball.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional view of a gear blade speed mechanism to which the present invention is applied, Figure 2 is an exploded perspective view of the main parts, and Figures 3, 4, 5, and 6 are cross sections taken along The figures show the neutral position, upshift, mid-return, and downshift, respectively. DESCRIPTION OF SYMBOLS 1...Change drum, 14...Do, ram bin, 15...Shift shaft, 20...Ball, 211
22...Folded portion, 23...Spring, 33.34...
Cam 20 Fig. 5 Fig. 411 Fig. 5

Claims (1)

[Claims] A change drum and a shift shaft are provided in parallel, a plurality of drum bins are provided at the end of the change drum in parallel to each other at intervals in the circumferential direction, and a ball that swings by the shift shaft is engaged with the bins. , in a gear transmission mechanism in which a change drum is rotated via a shear bin by the rocking of a ball, the ball is provided so as to be movable in the direction perpendicular to the shift MK axis, is biased toward the center of the shift shaft by a spring, and the tip of the ball is The ball is folded back toward the drum side in a roughly U-shape, and the folded part engages with a bottle that is far from the shift shaft. A gear transmission mechanism characterized by forming a cam that crosses over in a right angle direction.